Presentation Information
[O12-P96]Distribution of microplastics in the sediments of Obama Bay
*Rena Yamada1, *Sara Kaneda1, *Yuka Kimura1, *Tomoya Kamikubo1, *Shinpei Itoh1, *Yu Hirata1 (1. Fukui Prefectural Wakasa High School)
Keywords:
Seabed sediments,Microplastics,Nile Red staining,PET fibers,Source identification
Microplastic (MP) pollution has become an increasing environmental concern, and previous studies suggest that MPs drift through the ocean and eventually accumulate on the seafloor. Earlier investigations in Obama Bay indicated higher MP abundance during winter and a predominance of fibrous MPs in sediments. This study aims to quantify the wide-area distribution of MPs in the seabed of Obama Bay and to clarify their origins and environmental behavior. MPs were identified and quantified using Nile Red staining.
Sediment samples from the seabed of Obama Bay were processed through density separation, organic matter digestion, and fluorescence microscopy. Only fibrous MPs, which constituted the majority of observed particles, were counted. Component identification was performed by comparing fluorescence characteristics with reference images of various plastics and natural materials.
Blue–purple fibrous particles, likely PET based on fluorescence patterns, were detected in many samples. MP abundance was particularly high along a straight transect from the bay mouth to the inner bay, with the highest concentration at site 9, whereas off-transect sites showed lower levels. The predominance of PET fibers may be explained by their high density and co-sedimentation with fine particles. Transport by seasonal winds and Stokes drift, as well as land-based inputs via wastewater effluent and sludge-derived runoff, may contribute to the observed distribution. Future work will focus on identifying MP sources, including evaluating contributions from wastewater treatment effluent and potential re-entry from agricultural land.
Sediment samples from the seabed of Obama Bay were processed through density separation, organic matter digestion, and fluorescence microscopy. Only fibrous MPs, which constituted the majority of observed particles, were counted. Component identification was performed by comparing fluorescence characteristics with reference images of various plastics and natural materials.
Blue–purple fibrous particles, likely PET based on fluorescence patterns, were detected in many samples. MP abundance was particularly high along a straight transect from the bay mouth to the inner bay, with the highest concentration at site 9, whereas off-transect sites showed lower levels. The predominance of PET fibers may be explained by their high density and co-sedimentation with fine particles. Transport by seasonal winds and Stokes drift, as well as land-based inputs via wastewater effluent and sludge-derived runoff, may contribute to the observed distribution. Future work will focus on identifying MP sources, including evaluating contributions from wastewater treatment effluent and potential re-entry from agricultural land.